SEPARATION OF FERMENTATION PRODUCTS BY MEMBRANE TECHNIQUES - PART-III- CONTINUOUS ISOLATION OF LACTIC-ACID BY FACILITATED MEMBRANE EXTRACTION

Facilitated membrane extraction (FME) has been examined for the contin uous isolation of lactic acid from its dilute solutions. The technique is intended for continuous fermentation technology, with the pH of a broth regulated by extraction of the acid. Standard dialysis membranes and a conventional diffusion dialyzer were the equipment used for car rying out the separation. By FME, slow diffusional transport across a membrane is accelerated by the neutralization of an acid in the receiv ing side of a dialyzer. By using this technique the fluxes of lactic a cid were found to be 0.7-1.3 mol.m(-2)h(-1) (pH 11.7-12.8) against 0.0 13-0.015 mol.m(-2).h(-1) reported for conventional diffusion dialysis (the same feed, C-acid = 0.01 mol.dm(-3)). The accumulation of lactate in a permeate established experimentally was 0.5-0.6 mol.dm(-3). The concentration of lactic acid left in a feed after extraction was 10(-3 )-10(-4) mol.dm(-3). FME integrated with electrodialysis seems to offe r an effective separation system for continuous fermentation technolog y.